Authentication is not needed if
- you're sending emails to recipients on that server
- you're logged in on that server (for example by using webmail)
- are sending from an IP address listed in mynetworks in /etc/postfix/main.cf.

2. When I tried to use option My outgoing smtp requires auth, I can't send email

Authentication is not needed if
- you're sending emails to recipients on that server
- you're logged in on that server (for example by using webmail)
- are sending from an IP address listed in mynetworks in /etc/postfix/main.cf.

Click to expand...

on main.cf, i only set mynetworks to 127.0.0.1/8
I'm sending using outlook
If sending to onother email such as yahoo.com, mail.log shows me
Relay access denied --> seems to be good
But if I using same auth, can't send email.